1、BRITISH STANDARD BS 5193:1991 ISO 6745:1990 Specification for Zinc phosphate pigments for paintsBS5193:1991 This British Standard, having been prepared under the directionof the Pigments, Paints and Varnishes Standards Policy Committee, was published under the authority of the Standards Board and co
2、mes into effect on 30April1991 BSI 11-1999 First published February 1975 Second edition April 1991 The following BSI references relate to the work on this standard: Committee reference PVC/1 Draft for comment 85/51595 DC ISBN 0 580 19552 X Committees responsible for this British Standard The prepara
3、tion of this British Standard was entrusted by the Pigments, Paints and Varnishes Standards Policy Committee (PVC/-) to Technical Committee PVC/1, upon which the following bodies were represented: Aluminium Powder and Paste Association British Cement Association British Railways Board Chemical Indus
4、tries Association Oil and Colour Chemists Association Paintmakers Association of Great Britain Ltd. Titanium Pigment Manufacturers Technical Committee Zinc Development Association Amendments issued since publication Amd. No. Date CommentsBS5193:1991 BSI 11-1999 i Contents Page Committees responsible
5、 Inside front cover National foreword ii 1 Scope 1 2 Normative references 1 3 Definition 1 4 Classification 1 5 Required characteristics and associated tolerances 1 6 Sampling 1 7 Determination of loss on ignition 2 8 Determination of zinc content 3 9 Determination of phosphate content 3 10 Test rep
6、ort 6 Table 1 Essential requirements 2 Table 2 Conditional requirement 2 Publication(s) referred to Inside back coverBS5193:1991 ii BSI 11-1999 National foreword This British Standard has been prepared under the direction of the Pigments, Paints and Varnishes Standards Policy Committee. It is identi
7、cal with ISO6745:1990 “Zinc phosphate pigments for paints Specifications and methods of test”, published by the International Organization for Standardization (ISO). It supersedes BS5193:1975, which is withdrawn. In the first edition of this standard, only one type of product was specified. In this
8、revision, three types are specified, of which type1 corresponds to the zinc phosphate dihydrate pigment specified in the first edition. The type3 pigment corresponds to zinc phosphate tetrahydrate, while the type2 pigment corresponds to mixtures of the other two types. In specifying products for com
9、pliance with this standard, users should stipulate the particular type by stating the number and date of this British Standard and the type in the form BS5193-1:1991 or BS5193-2:1991 or BS5193-3:1991. Except for the degree of hydration, the requirements for the three types are identical, but there a
10、re some differences from those specified in the first edition of this standard. The minimum resistivity of the aqueous extract has been reduced to compensate for a change in the pigment dispersion concentration, and evidence has been presented to show that this minimum resistivity satisfactorily res
11、tricts the content of chloride and sulphate ions. The maximum permissible residue on sieve has been increased because a sieve of63m mesh aperture size has been replaced by one of45m. Limits on the permissible density have been introduced as a replacement for an unspecified agreed tamped volume. The
12、Technical Committee has reviewed the provisions of ISO385-1:1984, ISO648:1977 and ISO787-10:1981, to which reference is made in the text, and has decided that they are acceptable for use in conjunction with this standard. ISO385-1:1984 is related to BS846:1985, ISO648:1977 is related to BS1583:1986,
13、 and ISO787-10:1981 is related to BS3483-B8:1982. Cross-references International Standard Corresponding British Standard BS3483 Methods for testing pigments for paints ISO787-5:1980 Part B7:1982 Determination of oil absorption value (Identical) ISO787-7:1981 Part B3:1982 Determination of residue on
14、sieve (watermethod, using a manual procedure) (Identical) ISO787-9:1981 Part C4:1982 Determination of pH value of an aqueous suspension (Identical) ISO787-14:1973 Part C5:1974 Determination of resistivity of aqueous extract (Technically equivalent) ISO842:1984 BS4726:1986 Methods for sampling raw ma
15、terials for paints and varnishes (Identical) ISO3696:1987 BS3978:1987 Specification for water for laboratory use (Identical) ISO4793:1980 BS1752:1983 Specification for laboratory sintered or fritted filters including porosity grading (Identical)BS5193:1991 BSI 11-1999 iii A British Standard does not
16、 purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside fr
17、ont cover, pages i to iv, pages1to6, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.iv blankBS5193:1991 BSI 11-1999 1 1 Scope This Internation
18、al Standard specifies the requirements and the corresponding methods of test for zinc phosphate pigments suitable for use in corrosion-inhibiting paints. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this Internation
19、al Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Membe
20、rs of IEC and ISO maintain registers of currently valid International Standards. ISO385-1:1984, Laboratory glassware Burettes Part1: General requirements. ISO648:1977, Laboratory glassware One-mark pipettes. ISO787-5:1980, General methods of test for pigments and extenders Part5: Determination of oi
21、l absorption value. ISO787-7:1981, General methods of test for pigments and extenders Part7: Determination of residue on sieve Water method Manual procedure. ISO787-9:1981, General methods of test for pigments and extenders Part9: Determination of pH value of an aqueous suspension. ISO787-10:1981, G
22、eneral methods of test for pigments and extenders Part10: Determination of density Pyknometer method. ISO787-14:1973, General methods of test for pigments Part14: Determination of resistivity of aqueous extract (Printed together with Part13 and Part17). ISO842:1984, Raw materials for paints and varn
23、ishes Sampling. ISO3696:1987, Water for analytical laboratory use Specification and test methods. ISO4793:1980, Laboratory sintered (fritted) filters Porosity grading, classification and designation. 3 Definition For the purposes of this International Standard, the following definition applies. zinc
24、 phosphate pigment a white corrosion-inhibiting pigment consisting either predominantly of zinc phosphate dihydrate Zn 3 (PO 4 ) 2 .2H 2 O or of a mixture of zinc phosphate dihydrate and zinc phosphate tetrahydrate Zn 3 (PO 4 ) 2 .4H 2 O or predominantly of zinc phosphate tetrahydrate, and free from
25、 extenders and other pigments 4 Classification In this International Standard, zinc phosphate pigments are classified as one of the following three types: Type1: consisting predominantly of zinc phosphate dihydrate and exhibiting a loss on ignition at600 C of greater than8,5% (m/m) but less than or
26、equal to10,0% (m/m). Type2: consisting essentially of a mixture of zinc phosphate dihydrate and zinc phosphate tetrahydrate and exhibiting a loss on ignition at600 C of greater than10,0% (m/m) but less than or equal to13,0% (m/m). Type3: consisting predominantly of zinc phosphate tetrahydrate and ex
27、hibiting a loss on ignition at600 C of greater than13,0% (m/m) but less than or equal to16,0% (m/m). NOTE 1The corrosion-inhibiting properties of the various types of zinc phosphate pigment may differ. 5 Required characteristics and associated tolerances 5.1 For zinc phosphate pigments complying wit
28、h this International Standard, the essential requirements are specified in Table 1 and the conditional requirement is listed in Table 2. The conditional requirement shall be specified by agreement between the interested parties. 5.2 The agreed reference pigment referred to in Table 2 shall comply wi
29、th the requirements of Table 1. 6 Sampling Take a representative sample of the product to be tested, as described in ISO842.BS5193:1991 2 BSI 11-1999 7 Determination of loss on ignition 7.1 Apparatus Use ordinary laboratory apparatus and glassware complying with the requirements of the relevant Inte
30、rnational Standards (seeclause2), together with the following. 7.1.1 Muffle furnace, capable of being maintained at600 C 20 C. 7.1.2 Silica crucible 7.1.3 Balance, capable of weighing to0,1mg. 7.2 Procedure Carry out the determination in duplicate. Heat the crucible(7.1.2) for30min in the muffle fur
31、nace(7.1.1), maintained at600 C 20 C. Allow to cool to room temperature in a desiccator containing an active desiccant and weigh the crucible. Weigh, to the nearest0,1mg, approximately2g to3g of the sample (seeclause6) into the previously ignited and tared crucible. Heat the crucible and test portio
32、n for30min in the muffle furnace, maintained at600 C 20 C. Allow to cool to room temperature in the desiccator and reweigh. Repeat the heating, cooling and weighing operations until the results of successive weighings do not differ by more than1mg. NOTE 2Zinc phosphate, especially the dihydrate, is
33、hygroscopic. Retain the ignited pigment for the determinations described in clause8 and clause9. 7.3 Expression of results Calculate the loss on ignition LI of the pigment, expressed as a percentage by mass, using the equation where If the two determinations differ by more than0,2%(m/m), repeat the
34、procedure. Calculate the mean of two valid determinations and report the result to the nearest0,1%(m/m). Table 1 Essential requirements Table 2 Conditional requirement m 0 is the mass, in grams, of the test portion before ignition; m 1 is the mass, in grams, of the lest portion after ignition. Chara
35、cteristic Unit Requirement Method of test Type 1 Type 2 Type 3 Loss on ignition, LI %(m/m) 8,5LIu 10,0 10,0LIu 13,0 13,0LIu 16,0 See clause7 Zinc content (based on the ignited test portion), w(Zn) %(m/m) 50,5u w(Zn)u 52,0 See clause8 Phosphate content (based on the ignited test portion), w(PO 4 ) %(
36、m/m) 47,0u w(PO 4 )u 49,0 See clause9 Resistivity of the aqueous extract 7m min.65 ISO787-14 pH-value of the aqueous suspension 6,0u pHu 8,0 ISO787-9 Density, g/cm 3 3,0u u 3,6 ISO787-10 Residue on sieve(454m) %(m/m) max.0,5 ISO787-7 Characteristic Requirement Method of test Oil-absorption value Sha
37、ll not differ by more than10% from that of the agreed reference pigment(see5.2) ISO787-5BS5193:1991 BSI 11-1999 3 8 Determination of zinc content 8.1 Principle Dissolution of a test portion in hydrochloric acid. Complexometric titration of the zinc with EDTA solution at pH5,0. 8.2 Reagents During th
38、e analysis, use only reagents of recognized analytical grade and only water of at least grade3 purity as defined in ISO3696. WARNING Use the reagents in accordance with the appropriate health and safety regulations. 8.2.1 Hydrochloric acid, diluted1+4. Add1 part by volume of concentrated hydrochlori
39、c acid approximately37%(m/m), . 1,19g/ml to4parts by volume of water. 8.2.2 EDTA, standard volumetric solution, c(EDTA)=0,025mol/l. Dissolve9,3063g of disodium ethylenediamine tetraacetate dihydrate (EDTA disodium salt) in water in a1000ml one-mark volumetric flask, dilute to the mark and mix well.
40、8.2.3 Xylenol orange mixture Add1g of xylenol orange to100g of sodium chloride (or potassium nitrate) and mix well. 8.2.4 Hexamethylene tetramine 8.3 Apparatus Use ordinary laboratory apparatus and glassware complying with the requirements of the relevant International Standards (seeclause2). 8.4 Pr
41、ocedure Carry out the determination in duplicate. 8.4.1 Preparation of the test solution Weigh out, to the nearest0,1mg, approximately1g of pigment which has been freshly ignited as described in7.2. Boil this test portion with50ml of1+4 hydrochloric acid(8.2.1) for20min. After cooling to room temper
42、ature, transfer the solution to a500ml one-mark volumetric flask, dilute to the mark and mix well. NOTE 3This test solution is also used for the determination of the phosphate content as described in9.1. 8.4.2 Determination Pipette50ml of the test solution prepared in8.4.1 into a150ml beaker. Add0,1
43、g of xylenol orange mixture(8.2.3), followed by small portions of hexamethylene tetramine(8.2.4) until the colour changes from yellow to pink. Then add an excess of0,4g to0,5g of hexamethylene tetramine. Afterwards, whilst stirring, titrate with EDTA solution(8.2.2) until the colour just changesto y
44、ellow. 8.5 Expression of results 8.5.1 Calculation Calculate the zinc content w(Zn) of the pigment, expressed as a percentage by mass, using the equation where If the two determinations differ by more than0,2%(m/m), repeat the procedure. Calculate the mean of two valid determinations and report the
45、result to the nearest0,1%(m/m). 8.5.2 Precision No precision data are currently available. 9 Determination of phosphate content For the determination of the phosphate content, two methods (one gravimetric, the other titrimetric) are specified. The method to be used shall be agreed on between the int
46、erested parties. The gravimetric method(9.1) shall be used as the referee method in cases of dispute. V is the volume, in millilitres, of the EDTA solution(8.2.2) used; m 2 is the mass, in grams, of the test portion; 1,634310 3 is the factor for the conversion of millilitres of EDTA solution, c(EDTA
47、)=0,025mol/l, to grams ofZn.BS5193:1991 4 BSI 11-1999 9.1 Gravimetric method 9.1.1 Principle Addition of citromolybdate reagent to a portion of the test solution prepared for the determination of zinc content (see8.4.1) and weighing of the precipitated quinoline phosphomolybdate. 9.1.2 Citromolybdat
48、e reagent Prepare the reagent as follows: a) Dissolve70g of disodium molybdate dihydrate (Na 2 MoO 4 .2H 2 O) in150ml of water. b) Dissolve60g of citric acid monohydrate (C 6 H 8 O 7 .H 2 O) in150ml of water and add85ml ofconcentrated nitric acid approximately65%(m/m), . 1,40g/ml. c) Add solution a)
49、 to solution b), mixing continuously during the addition. d) Add35ml of concentrated nitric acid, followed by5ml of freshly distilled quinoline, to100ml of water. e) Pour solution d) into solution c) and mix well. Allow to stand for at least12h (for example, overnight) and filter through a sintered-glass filter crucible(9.1.3.1). f) Add280ml of acetone to solution e) and dilute to1000ml with water. Keep this solution in a securely stoppered flask and store away from light, but no longer than1 week. 9.1.3
